Continuing its losing streak for the fourth straight session, the Bombay Stock Exchange benchmark Sensex shed 50 points in the opening trade on Monday on profit-booking.
The 30-share barometer, which lost over 775 points in the previous three sessions, lost 50 points more to trade at 20,106.89 in the opening trade.
Similarly, the wide-based National Stock Exchange index Nifty skid by 20 points to 6,051.65.
Brokers said trading sentiments turned cautious after continued selling by retail investors at prevailing higher levels.
However, bucking the weak trend, Tata steel stocks traded 1.90 per cent higher at Rs 617.80 per piece on the back of the company's better-than-estimated quarterly earnings.
In other Asian markets, the Hong Kong's Hang Seng index was quoting higher by 0.52 per cent, while Japanese Nikkei was marginally up by 0.59 per cent in the morning trade.